1. Field of the Invention
This invention relates to a file management system which gives flexibility to the sizes of divided files set in a memory in an electronic apparatus such as an IC card containing a nonvolatile memory and an IC chip having a control element, like a CPU, that controls the memory.
2. Description of the Related Art
Presently, IC cards containing nonvolatile data memories and IC chips with control elements, including CPUs, that control those memories are attracting attention as portable data process/memory mediums.
An IC card of this type is known in U.S. Pat. No. 5,226,155 in which a built-in data memory is divided into a plurality of files and data to be utilized when the card is used in an application is stored in each file. By entering an application identification name into the IC card from an external device, only a corresponding file is selectively brought into a usable state. With this file selection, multipurpose application can be achieved by grouping a plurality of application data items into files and storing them into a single IC card. These application files include a plurality of data files for storing data such as transaction data.
These application files are added with size data. When the data files are created in the application files, whether or not these data files can be created on the basis of the size of memory used for these files and the size given to the application files. By doing this, the memory areas of applications are prevented from interfering with one another.
With the above method, however, the sizes of application files are set previously, which therefore makes it impossible to change the sizes later. For example, it is assumed that 1000 bytes are given to a file used in application A and 2000 bytes are given to a file used in application B. Even if only 500 bytes out of the given 1000 bytes are used in application A and another 500 bytes are required in application B in the course of executing the two applications, they must be executed within the range of the given size.
Accordingly, the file (500 bytes) for use in application B will not suffice the efficiency of execution for an application.